The present invention relates to a method for fabricating a semiconductor device; and, more particularly, to a method for fabricating a transistor using an epitaxial channel and a laser thermal treatment.
Recently, low energy ion-implantation and epitaxial channel processes have been considered as a technique to form highly integrated circuits having a line width of 0.1 xcexcm or less because these processes may improve the short channel effect (SCE) at a low threshold voltage.
FIG. 1 is a cross-sectional view illustrating a method for forming a conventional semiconductor device. As shown in FIG. 1, a channel ion-implantation layer 12 and an epitaxial silicon layer 13 are formed on a semiconductor substrate 11 in this order. Accordingly, to guarantee the quality of the semiconductor device, at least two conditions should be satisfied. First, a profile of the implanted boron ions should be maintained over the epitaxial growing process and the following thermal treatments. Second, since the epitaxial silicon layer 13 is used as a channel, a high-quality epitaxial layer should grow without any interfacial boundary between the epitaxial silicon layer 13 and the semiconductor substrate 11.
However, as of now, the doping profile of the boron ions deteriorates at a temperature of 800xc2x0 C. for the following epitaxial growing and a rapid thermal processing (RTP) at 950xc2x0 C. for about 20 seconds. Also, since the epitaxial silicon layer grows on the semiconductor substrate into which the impurities are implanted, the impurities, such as oxygen, may form a layer between the epitaxial silicon layer and the semiconductor substrate. Such a layer may damage the physical characteristics of the epitaxial channel.
A method for forming electrically stable semiconductor device by thermally treating a semiconductor substrate with a laser is disclosed.
A method for forming a thin semiconductor device having a decreased tunneling leakage current is also disclosed.
A method for forming a semiconductor device is disclosed which comprises the steps of: forming a delta doping layer having impurity ions on a semiconductor substrate with a low energy ion-implantation; activating the impurity ions within the delta doping layer by thermally treating a surface of the semiconductor substrate with a laser; forming a channel epitaxial layer on the semiconductor substrate; forming a gate insulation layer and a gate electrode on the channel epitaxial layer in this order; and forming a source/drain region in the semiconductor substrate.